Cordless impact driver - Where does the power come from?

[Roy66]

I've heard a lot of great things about cordless impact drivers. It seems that every article I read on them mentions that they have a longer battery life than regular cordless drills because they don't use any additional battery power to create those powerful impacts.

How can this be true? Surely that power must be coming from somewhere?

Cheers,

R

 

[foxhole]

They use an internal spring which is cocked and released in a similar way to a hand impact driver but at far greater speed.

 

[Roy66]

But battery power must be being used to pull back this spring, so why are people online saying that no additional power is used?

 

[dhutch]

But battery power must be being used to pull back this spring, so why are people online saying that no additional power is used?

Because there idiots and impact drivers have bigger batteries...

There also an agument that an impact driver will use less power to extract a seazed bolt by freeing with impact than brute force I guess. But there not really comparable items,.


Daniel

 

[joe-90]

Similar to how an SDS drill will out perform a rotary drill even thought the rotary drill is much higher powered.

 

[noseall]

Impact drivers use energy more wisely to convert the torque into what it is supposed to do as opposed to breaking your wrist.

 

[Jackrae]

As a somewhat obscure analogy, you might consider trying to undo a very tight nut. You can pull (steady torque) and grunt on the spanner until you are blue in the face and it still doesn't turn : or you can give the spanner a sharp hit with a hammer (impact torque) and the nut spins free. You are the power source for both circumstances but you know which took the lesser effort.

 

[R5GTT]

Impact drivers use a rotary impact action. Because the "impact" only puts the machine under maximum load for a split second it allows the battery to last longer.

To explain - if you put a screw in with a combi or drill driver the tool us under load for however long it takes to put the screw in. With an impact driver it's effectively on off on off on off hence why it doesn't drain the batteries.

There's no spring mechanism in them though?